[Studies in Computational Intelligence 481] Artur Babiarz, Robert Bieda, Karol Jędrasiak, Aleksander Nawrat (auth.), Aleksander Nawrat, Zygmunt Kuś (eds.) - Vision Based Systemsfor UAV Applications (2013, Sprin

94 Construction of Image Acquisition Devices Used in UAV Applications
Unmanned Aerial Vehicles are utilized by a variety of uniform services and armed
forces. They are also used by search and rescue units. All of the above institutions
commonly operate regardless the weather and day/night conditions. This is associated
with many challenges to overcome by complex algorithms and innovative
video acquisition devices. Combustion engines used in larger UAVs introduce a
large amount of high frequency
Additionally during flight in harsh conditions the wind speed is sufficient for
unexpected UAV rotation. It has to be compensated by some kind of mechanism
capable of 3-DOF rotating camera line of sight. It could be achieved by mechanical
construction called gimbal, combination of lenses and optical mechanism or a
wide angle of sight e.g. fish eye camera. However operating an UAV is harsh
weather conditions can lead to blockage of the mechanical mechanism. In the
chapter is also presented an innovative omnidirectional video acquisition device
that is composed from multiple cameras with a line of sight covering half of the
sphere. There is no mechanical or optical mechanism therefore it is free from the
mentioned disadvantages. Additionally due to its multiple camera nature the combined
video stream resolution is many times greater than in traditionally used
cameras. Moreover it is possible to almost immediately rotate the image by any
angle.
Unfortunately traditionally used visible light cameras cover only a small part of
the magnetic spectrum and are easily covered by dust, smoke, fog, etc. In order to
continue aerial observation thermal imaging cameras have to be used. Such devices
can be mounted onboard an UAV and used for observation, target detection,
tracking and recognition in challenging weather conditions and low light conditions.
Thus providing full day/night observation capability. Thermal imaging cameras
along with visible light cameras can be mounted in the single gimbal in order
to provide the possibility for image fusion resulting in highlighting the most valuable
information from both video sources.
Nowadays, image acquisition devices are mainly used by human operators or
large tactical or strategic class UAVs. Therefore there is a need for innovative
video sources that are characterized by small weight, low energy consumption and
at the same time high resistance to vibrations, shock and temperature. It is a challenging
task for developers and difficult compromises have to be made. The chapter
presents many of the mentioned challenges along with example solutions and
useful and practical suggestions. One of such practical suggestions in an omnidirectional
video acquisition device. It is an innovative concept that may find many
applications both civilian and military. It can be used to observe areas that may
need wide area monitoring such as shops, banks, petrol stations. In military installations
OVAD may be used to patrol the area from the ground or from the air.
Application allows capturing images from chosen camera. It is possible to immediately
switch between cameras or also move around the panorama created from
multiple video streams, like in rotating camera. Panorama contains combined view
of entire area around device.